In an interview with GameIndustry, former EA boss Bing Gordon stated due to the increased competition from the mobile market, Nintendo will be the first to drop out from the "Big 3" console hardware makers.
He stated they are already on track with the Wii U being the start due to the tablet and mobile market itself and not due to their own business decisions. In order to stand a chance in the future as a hardware maker, Nintendo would have to form a partnership with Apple.
His reasoning to why Nintendo would drop out included comparisons to Sega when they were a hardware maker and the "pinch" from the huge competition mobile devices are creating against their handhelds which is seen as their main stronghold. He did admit that Nintendo hasn't really committed the same level of huge mistakes that Sega did which lead to their demise from the hardware market.
He did feel Miyamoto is the wild card for Nintendo's future since he;s seen as the one who has ensured Nintendo survived all the challenges its faced so far but Nintendo's biggest challenge ever will occur once he's gone.
In terms of the other hardware makers, he felt Microsoft has nothing to fear due to the Xbox 360 being their "consumer miracle" console while Sony's future is tougher to predict due to their multiple divisions all impacting each other.